This invention relates generally to steerable vehicles, and more particularly to drivable platforms capable of being steered at any angle through 360.degree..
Drivable, steerable platforms have been used in industrial and agricultural equipment. Known prior art devices utilize complex mechanical linkages to effectuate steering. The mechanical steering linkages are actuated by hydraulic cylinders driven by a selectively actuated hydraulic pump. The wheels can typically be steered through angles greater than 180.degree.. However, due to the mechanical limitations of the linkage system the wheels cannot be steered through any angle between 0.degree. and 360.degree. degrees.
Typically, such platforms receive their driving power from an internal combustion engine or an electric motor driven by a battery. The engine or motor drive a hydraulic pump which delivers fluid under pressure to hydraulic motors attached to each wheel of the platform. The hydraulic motors that drive the wheels must be carefully regulated for the wheels to all turn at the same speed.
Other known prior art devices include cable steering systems. These devices include a plurality of spools on which cable is wound and unwound to effectuate steering. In such systems, the wheels of the vehicle cannot be steered through any angle in the continuous range 0.degree. to 360.degree..
The control apparatus of known prior art devices permit only limited control of a vehicle's steering and driving. One such remotely controlled device can be steered only through relatively large angular turns. Another such device operates only on the principle of random motion within a boundary.
The known prior art devices are generally characterized by complex mechanical and/or hydraulic construction and relatively poor control over steering and driving.